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K-jet warm-up issue

Hotdoggin

New member
Joined
Oct 24, 2014
Location
Tallahassee, FL
1983 244T - Non-IC - fresh stage 0

Car has been sitting since 2007 - started monthly. Runs and drives right now, boosts and moves, the problem is... it won't do any of that until it's almost-full warm. On first startup it revs and runs fine for about 20 seconds. Idles perfect the whole time, but for about two minutes it won't take any throttle. It'll bog off idle and frontfire until it gets above 1500 or so, and miss a little until 3k, then rev out. Runs pretty well after that, though. Drivable and really gets moving once out of first. Never acts like it wants to die. My assumption is WUR based on how it acts before the car is fully warm. However, pouring over the K-jet green book, and over on the Merc/VW/Porsche forums... this isn't really a WUR-type symptom. I have two spares I can rebuild but would like to pin down the issue before throwing parts at it. Thanks!

Recent out-of-hibernation maintenance:

Bosch plugs, cap, rotor, Kingsbourne wires
New fuel filter and pumps, replaced fuel accumulator
All new vacuum lines
New fuel pump relay
Fresh fluids in all holes
Harness was replaced before it was parked

JmS3SHtl.jpg
 
Do you have a fuel pressure gauge? If so, what's the pump dead head pressure and return pressure cold and warm?
 
I'll have to check and see if the shop has all the proper fittings. So you want pressure right after the filter, and at the return junction right near the filter?
 
The fuel pressure gauge is connected to the line that goes from the center of the fuel distributor to the WUR. The gauge has a valve to direct the fuel either to the gauge only to read system pressure or to the WUR to read return pressure.

TurboK-JetFuelPressureGauge.jpg


Don't bother checking pump dead head pressure unless you have a gauge that can handle the pressure. System pressure is what's important.
 
Alright, just poking around and we do not have that setup. Everything I've been able to find regarding kjet fuel pressure kits has led to the tbricks gauge, and a dead JCWHITNEY part number. Has there been an updated kit? Or am i going to be cobbling one together?
 
Make sure the plug gap is proper at .028".

For a fuel pressure tester. Pelican parts used to sell one for quite a bit of money. I don't know who sells them anymore besides them but there may be another place. These folks do kjet service and repair.
https://www.deloreanautoparts.com/delorean-parts/fuel-injection.html

I have not used them but they seem to be making Delorean owners pretty happy. Scroll down the left side for kjet aka CIS information.
 
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It's been a few years...actually longer...since I drove/worked on a K-Jet car.

That being said, any information is from a long and getting weak memory.

I remember using a separate gage on both components...one on the center connection on the fuel distributor and another on the Warm Up Regulator (WUR) to compare pressure differential.

I made each connection/hose barb to the two components and from there standard WOG gages with a piece of fuel hose.

Does that not give the same result as the tester shown in the post by you hiperfauto?
Or is there any added benefit to having a 3 way valve between each gage?

Just curious.
 
The three way valve allows measurements of both distributor regulator pressure and WRU regulator on one gauge.
 
It's taken me quite a bit longer than anticipated, but I now have OE Volvo fuel pressure gauges and adapters available for rent. I have kits for K-Jet, LH-Jet without a schrader and LH-Jet with a schrader.

This is the turbo K-Jet set up. I even have the OE Volvo fuel pump bypass relay.

K-JetFuelPressureGauge.jpg


The gauges have recently been calibrated and all the rubber hoses are new.
 
Well, I suspect it'd make more sense to rent it from you. While it's here, I can source out the proper parts to make my own. What's the rental fee?
 
Yikes! While I value this as an option, and understand the sizable deposit... taking into consideration that I own a damn CIS car, I think it'd behoove me to spend the money on purchasing one. Looking on that Delorean page... they have a permanent control pressure gauge they install. I may go that route, alternatively, they too have the full CIS kit. dl242gt, THANK YOU for that resource.
 
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I need to be sure the gauge comes back, hence the large deposit. I couldn't replace it for $200. The real expense is shipping. The padded container I got from Harbor Freight doesn't fit in a large flat rate box, so USPS wants $30 the ship to the east coast.
 
I 100% understand! That is a very rare, and specific piece of kit. I think it'd be pretty wise of me to have one on hand, surely I'm going to have more issues as this is going to be in my stable for a long time. I just hope it doesn't keep separating me from all my money. :lol:
 
For the DIY tester, you can get poor quality, but usable, M8 and M10 banjo to hose fittings either here:
https://www.belmetric.com/eye-fittings-for-rubber-hose-c-1041_855_1135/?zenid=8jbsvfcir5cdj73hutid9cjm32

or ebay from the UK here
https://www.ebay.com/sch/i.html?_odkw=M8+fuel+banjo&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XM8+fuel+banjo+fitting.TRS0&_nkw=M8+fuel+banjo+fitting&_sacat=0

I originally tried to get better quality fittings from the Texas place, but they got confused when I told them I wanted the same hose barb size for both fittings and then shipped the wrong parts. (Their web pictures/descriptions were also not accurate at the time.)

To use the DIY tester, you need to plumb in a standard fuel pressure gauge, with shutoff, and then replace the whole line from the CPR (awkwardly placed under the manifold) to the cobra/fuel distributor. The nicer Volvo tester lets you tap into just the fuel disti connection without the hassles of accessing the CPR connection, and without the problems of getting it to reseal once done.
 
Max cost below $54.93. Surly, anyone with the need for and interest in assembling such a tool will have the at least some of the items in their junk box or available at their local JY or Lowes. The gauge and valve are all you have to order on line.

Gauge - $8.82

https://www.ebay.com/itm/2-1-2-Util...d=111164930740&_trksid=p2047675.c100011.m1850

Valve - $9.44

https://www.ebay.com/itm/1-4-mini-b...d=121166506886&_trksid=p2047675.c100005.m1851

8mm x 1/4" banjo fitting - $6.90

https://www.ebay.com/itm/Turbo-Banj...ash=item44031ba638:g:MFUAAOSw3xJVafaB&vxp=mtr

10mm x 1/4" banjo fitting - $7.48

https://www.ebay.com/itm/6mm-or-1-4...ash=item4b292fbc5e:g:On4AAOSwdbxZ5KcJ&vxp=mtr

Post on the WANTED Thread for a hose from the distributor to the WUR.

4 - 1/4" fuel injector hose clamps $6.29 Check HF

https://www.ebay.com/itm/FUEL-INJEC...ash=item5d78691efd:g:zvAAAOSwQItT3Nzv&vxp=mtr

4 ft 1/4" high pressure fuel injector hose - Local auto parts store $12

Brass 1/4" barb x 1/8" female x 1/4" barb fitting $4.00 (Lowes)

Duct tape
Zip tie
Coat hanger
JB Weld

Total $54.93

P1090004.jpg


You sorta have to buy the valve and gauge.
 
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